Water drain for floating roof tanks



March 30, 1943. H. M. STEVENSON WATER DRAIN FOR FLOATING- ROOF TANKSFiled June 10, 1939 \\\\\\\\\\\N NN\\\\\\\\\N\NN\\\ \\\N\NN\\\\\\\\\\WN\\\\ \\\\\\\\N\\\ NN MN lI/I/I/IIl/l/II/ IIIIIIII III/ [$11 11/ Ill/jPatented Mar. 30, 1943 WATER DRAIN FOR FLOATING ROOF TANKS Hugh M.Stevenson, Houston, Tex., assignorto Standard Oil Development Company, acorporation of Delaware Application June 10, 1939, Serial No. 278,442

1 Claim.

The present invention is directed to an improvement in floating rooftanks and has a particular reference to means for preventing theaccumulation of water on the roofs of such tanks.

Various types of roof tanks are known in the art. In general, thefloating roof has a sliding fit with the inner walls of the tank whichis achieved by a ring of packing material around the circumference ofthe roof. Necessarily, this fit cannot be too tight, because it mustpermit free movement of the roof. For this reason, the preventionofleakage of water into the tank has always presented a problem.

It has been the practise to provide a sump on the floating roof for thecollection of water and a conduit from this sump to a point outside thetank for the drainage of the collected water. Because the roof ismovable the drainage pipe must necessarily be one which can be movedwith the roof. It has been the practice, therefore, to use a metaldrainage pipe composed of joints swingingly connected to each other andarranged inside the tank having one Of its ends connected to the sumpand the other connected to an outlet at the bottom of the tank. Thejoints in this drainage pipe have always been a source of trouble sincethey are inclined to leak and as soon as a leak develops it is necessaryfor workmen to enter the tank and repair it. Because of safetyrequirements, workmen cannot enter a tank until it has been wholly freedof toxic vapors and gases. The cleaning of a tank in this. mannerinvolves anexpenditure of several hundred dollars and when thisprocedure has to be repeated several times a year, its cost becomesprohibitive.

The principal object of the present invention is the provision of adrainage pipe for a floating roof which will eliminate the diflicultiesattending drainage pipes of known types and which will also makepossible a new method of replacement in which workmen need not enter thetank.

Specifically, the present invention resides in the provision of aflexible drainage pipe resistant to oil which is so connected to thesump at one end and to the bottom of the tank at the other that it canbe removed and replaced from the outside.

The present invention will be better understood from the followingdetailed description of the acompanying drawing in which the singlefigure is a vertical section through a floating roof tank, only part ofwhich is shown, showing the drainage pipe of 'the present invention inplace.

Referring to the drawing in detail, numeral l designates the verticalwall of a tank having a floating roof 2 which is provided with acircumferential seal 3 of conventional type which will permit the roofto slide along the surface of wall I. The roof is provided at its centerwith a sump 4 having a covering 5 and with a hatch 6 spaced a shortdistance from the sump and provided with a cover I.

Arranged in the wall of the sump is a packing 8 through which passes apipe 9 which extends from the sump to a point underneath the hatch whereit is held in place by a bracket Ill. The end of the pipe under thehatch terminates in a flange II to which is bolted a flange i2 carryinga nipple l3 which frictionally holds one end of a rubber-like hose M.This hose is preferably made of a synthetic rubber which is resistant tooil such as of polymerized butadiene, chlorprene, or the like. The hoseis made...in -a--conventional manner with fiber reinforcement and inlaminated form. It is sufficient if the outside layer of the hose ismade of oil resistant material. For safety it is preferred to make boththe outside and inside layers of the hose of the aforesaid syntheticrubber. In order to relieve the load on the friction between the hoseand the nipple the hose is provided a short distance from thisconnection with a clamp l5 which is connected to a chain l6 anchored inthe hatch opening.

Near its lower end, the tank is provided with an opening in which isWelded a pipe I! greater in diameter than the hose I4, The outer end ofthis pipe is providedwith a flange i8 to which is bolted another flange[9 through which is screwed a pipe 20 to the inner end of which the hosei4 is frictionally connected and bound with clamps 2 i. The outer end ofthe pipe 20 is pro vided with a gate valve 22, so that if the hoseshould spring a leak, loss of oil can be prevented.

When it is necessary to repair the hose M, a line is connected to itsupper end through the hatch I and its upper end is then disconnectedfrom nipple l3 and chain it. Either then, or before, the oil is drainedout of the tank to a point below the level of pipe l'i. Flange I9 isthen removed and the hose is drawn out through pipe I! carrying theaforesaid line with it. The end of the line after it is pulled out ofpipe [1 is connected to the upper end of the replacement hose which isthen pulled up into place through hatch I and connected to nipple I3 andchain IS. The lower end of the replacement hose is connected to pipe 20in the manner shown and flange I 9 is bolted back in place.

It will be apparent that changes can be made intthe specificconstruction shown without departing from'the scope of applicant'sinvention. While applicant has mentioned specific synthetic rubberswhich may be employed, theremay be other flexible materials having oilresistivity which'canalso be utilized and some such materials may, belater developed, which will be applicable. It may be mentioned also thatapplicants invention ofiers considerable advantages over presentpractices even when a rubber hose is employed, because the cost of suchhose and its replacement, even though such replacement is frequentlynecessary, islless, than the expense incurred with the use of thedrainage pipe hitherto employed. v M 1 v The nature and'objects of -thepresent invention havingbeen thus described and illustrated,

what is claimed as new andvuseful and is desired to be secured byLetters Patent is:

In a floating roof tank'a sump for collection of water on said roof, ahatch in said roof adjavcent said sump, an outlet nipple on said sumphaving its end projecting into the interior of said tank at a pointbeneath said hatch and adjacent thereto, a short pipe arranged in thewall of the tank adjacent the bottom end to project into' the interiorof the tank and provided with a flange at its outer end, a mating flangedetach- HUGH M. s'rEv NsoN.

